The present invention relates to a manual spray-coating gun.
A manual spray gun for powder or granulate coating material is known from U.S. Pat. No. 4,196,465. It contains a barrel and a grip. The index finger encloses a rigger. Squeezing the trigger switches ON the supply of coating material to the spray gun and releasing the trigger shuts it OFF. The electric power supply to one or more high-voltage electrodes electrostatically charging the coating material is switched ON and OFF simultaneously with squeezing and releasing the trigger. A high-voltage generator feeding the electrode is housed in the gun and by means of a low-voltage cable is connected to a low-voltage DC source and contains an oscillator, a transformer and a cascade circuit of resistors and capacitors. The powder coating material is pneumatically fed by a pump in the form of an injector of the design disclosed in the German patent document 1,266,685 C to the gun. Moreover it is known from the German patent document 34 02 945 C to mount a display on the back side of the gun to generate an optical signal as a function of the electrode""s voltage level. U.S. Pat. No. 4,441,656 discloses a manual spray gun to electrostatically coat objects with a liquid coating material. Its trigger allows opening or closing a valve housed in the gun and controlling the feed of coating material. Also guns are known in the state of the art that are designed with continuous liquid-coating feed during coating pauses, during which said feed is recirculated by the gun to the source of liquid.
The known spray coating guns is connected to an electric control unit several meters away and allowing adjusting the rate of coating material and the voltage level of the minimum of one high-voltage electrode.
In accordance with the invention, the control unit frequently is several meters away from the operator who in turn must stand near a coating station or cabin and must observe the spraying of the coating material onto an object to be coated. The invention offers the advantage that the operator is able to set the operational values directly by hand at the spray gun and therefore need not go to the control unit. This feature is especially significant when the operational values must be frequently adjusted to other coating conditions, for instance to bigger or lesser coating thicknesses and/or to match different objects, for instance uncoated or already coated objects, simple objects with large surfaces or complex objects with recesses and undercuts or apertures in the surface.
Further features of the invention are stated in the sub-claims.
The invention is applicable both to liquid and to powder or granulate coating material.